/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkHessian3DToVesselnessMeasureImageFilter_h
#define itkHessian3DToVesselnessMeasureImageFilter_h

#include "itkSymmetricSecondRankTensor.h"
#include "itkSymmetricEigenAnalysisImageFilter.h"

namespace itk
{
/** \class Hessian3DToVesselnessMeasureImageFilter
 * \brief Line filter to provide a vesselness measure for tubular objects from the
 * hessian matrix.
 *
 * The filter takes as input an image of hessian pixels
 * (SymmetricSecondRankTensor pixels) and preserves pixels that have
 * eigen values \f$ \lambda_3 \f$ close to 0 and \f$\lambda_2\f$ and \f$\lambda_1\f$ as
 * large negative values (for bright tubular structures).
 *
 * \f[ | \lambda_1 | < | \lambda_2 | < | \lambda_3 | \f]
 *
 * \par Notes:
 * The filter takes into account that the eigen values play a crucial role in
 * discrimintaitng shape and orientation of structures.
 *
 * \li Bright tubular structures will have low \f$\lambda_1\f$ and large negative
 * values of \f$\lambda_2\f$ and \f$\lambda_3\f$.
 * \li Conversely dark tubular structures will have a low value of
 * \f$\lambda_1\f$ and large positive values of \f$\lambda_2\f$ and
 * \f$\lambda_3\f$.
 * \li Bright plate like structures have low values of \f$\lambda_1\f$ and
 * \f$\lambda_2\f$ and large negative values of \f$\lambda_3\f$
 * \li Dark plate like structures have low values of \f$\lambda_1\f$ and
 * \f$\lambda_2\f$ and large positive values of \f$\lambda_3\f$
 * \li Bright spherical (blob) like structures have all three eigen values as
 * large negative numbers
 * \li Dark spherical (blob) like structures have all three eigen values as
 * large positive numbers
 *
 * This filter is used to discriminate the Bright tubular structures.
 *
 * \par References:
 * "3D Multi-scale line filter for segmentation and visualization of
 * curvilinear structures in medical images",
 * Yoshinobu Sato, Shin Nakajima, Hideki Atsumi, Thomas Koller,
 * Guido Gerig, Shigeyuki Yoshida, Ron Kikinis.
 *
 * http://www.spl.harvard.edu/archive/spl-pre2007/pages/papers/yoshi/
 *
 *
 * \sa HessianRecursiveGaussianImageFilter
 * \sa SymmetricEigenAnalysisImageFilter
 * \sa SymmetricSecondRankTensor
 *
 * \ingroup IntensityImageFilters TensorObjects
 *
 * \ingroup ITKImageFeature
 */

template< typename  TPixel >
class ITK_TEMPLATE_EXPORT Hessian3DToVesselnessMeasureImageFilter:public
  ImageToImageFilter< Image< SymmetricSecondRankTensor< double, 3 >, 3 >,
                      Image< TPixel, 3 > >
{
public:
  /** Standard class typedefs. */
  typedef Hessian3DToVesselnessMeasureImageFilter Self;
  typedef ImageToImageFilter<
    Image< SymmetricSecondRankTensor< double, 3 >, 3 >,
    Image< TPixel, 3 > >                    Superclass;

  typedef SmartPointer< Self >       Pointer;
  typedef SmartPointer< const Self > ConstPointer;

  typedef typename Superclass::InputImageType  InputImageType;
  typedef typename Superclass::OutputImageType OutputImageType;
  typedef typename InputImageType::PixelType   InputPixelType;
  typedef TPixel                               OutputPixelType;

  /** Image dimension = 3. */
  itkStaticConstMacro(ImageDimension, unsigned int,
                       InputImageType ::ImageDimension);
  itkStaticConstMacro(InputPixelDimension, unsigned int,
                      InputPixelType::Dimension);

  typedef  FixedArray< double, itkGetStaticConstMacro(InputPixelDimension) >
  EigenValueArrayType;
  typedef  Image< EigenValueArrayType, itkGetStaticConstMacro(ImageDimension) >
  EigenValueImageType;
  typedef   SymmetricEigenAnalysisImageFilter<
    InputImageType, EigenValueImageType >     EigenAnalysisFilterType;

  /** Run-time type information (and related methods).   */
  itkTypeMacro(Hessian3DToVesselnessMeasureImageFilter, ImageToImageFilter);

  /** Method for creation through the object factory. */
  itkNewMacro(Self);

  /** Set/Get macros for alpha_1. Please refer to
   * http://www.spl.harvard.edu/archive/spl-pre2007/pages/papers/yoshi/ */
  itkSetMacro(Alpha1, double);
  itkGetConstMacro(Alpha1, double);

  /** Set/Get macros for alpha_2. Please refer to
   * http://www.spl.harvard.edu/archive/spl-pre2007/pages/papers/yoshi/ */
  itkSetMacro(Alpha2, double);
  itkGetConstMacro(Alpha2, double);

#ifdef ITK_USE_CONCEPT_CHECKING
  // Begin concept checking
  itkConceptMacro( DoubleConvertibleToOutputCheck,
                   ( Concept::Convertible< double, OutputPixelType > ) );
  // End concept checking
#endif

protected:
  Hessian3DToVesselnessMeasureImageFilter();
  ~Hessian3DToVesselnessMeasureImageFilter() {}
  void PrintSelf(std::ostream & os, Indent indent) const ITK_OVERRIDE;

  /** Generate Data */
  void GenerateData(void) ITK_OVERRIDE;

private:
  ITK_DISALLOW_COPY_AND_ASSIGN(Hessian3DToVesselnessMeasureImageFilter);

  typename EigenAnalysisFilterType::Pointer m_SymmetricEigenValueFilter;

  double m_Alpha1;
  double m_Alpha2;
};
} // end namespace itk

#ifndef ITK_MANUAL_INSTANTIATION
#include "itkHessian3DToVesselnessMeasureImageFilter.hxx"
#endif

#endif
